Now, I have not located any GEMA statements about this "twelve musical works" (Other than that twitt) in english (my german sucks). So I'm at a loss here about GEMA stand (We all know Youtube's one). I will ask again tomorrow, see if I get an answer.

You express that .com is being used in a bad way (the ICE takedowns and intent to continue)

Neither Mike nor any other poster I read here is saying that the .com tld is being used the wrong way. I believe the intention and meaning behind Mike and other Americans here posting is about saving the .com tld, not boycott it.

Why would it need to be saved?
Well, I'm not an US-American and I will certainly avoid .com .net and such, don't want to be liable in the US for something legal in my country. (Same apply to the use of any other US company not only VeriSign, but that's another story) Non US residents will most probably do the same, and so .com will be the playground of US and US alone.
I, of course, do not care about that scenario, It's not my country economy (and legitimacy) suffering. If US wants to disconnect itself from the world, good for them, they can play withing their own net.
I believe some US residents are quite fearful of that scenario (they are right to be), and that's what they intend to prevent, not boycotting .com but saving it from the actions of a few misguided government agencies.

In Mexico the parliament have been using Hadopi as an example of fine law making (without mentioning all the controversy around it) to go for a 3strikes internet law in the nation. The intention on the ruling was then withdrew due to objections from the mexican internet community. I guess our 'diputados' (MP's) have starting to realize the impact of the mouth to mouth bad/good publicity provided by the internet voters. This possible bad publicity weighed more in the withdrew than the actual arguments given to illustrate how terrible this law was.